cathode

Etymology

It is borrowed from Ancient Greek κάθοδος (káthodos, “a going down, a way down”),^{[2][3][4][5][6]} from κατά (katá, “down”) and ὁδός (hodós, “way, path”).^{[2][3][4][5][6]} It was a learned coinage of 1834, paired with anode.^[3][7] Etymonline says that William Whewell proposed it and Michael Faraday published it,^[3] and Ayto likewise credits Whewell,^[7] whereas Barnhart and Klein say Faraday introduced it.^[4][6] The name refers to the path the current was thought to take from the negative pole,^[3][4] and Merriam-Webster Unabridged specifies the belief that the current passes from east to west.^[8] Etymonline calls the Greek noun for "way" of uncertain origin,^[3] while Ayto thinks it possibly related to Latin cēdō, the source of cede.^[7][8]

Earliest recorded meaning

The path by which an electric current leaves the electrolyte and passes into the negative pole, and the surface in contact with that pole: 1834, in Faraday's Experimental Researches in Electricity.^[2][3]

Semantic evolution

Faraday's term named a path or surface, and by 1840, in the Proceedings of the American Philosophical Society, it was used for the negative pole itself.^[2] The spelling kathode also occurred for a time.^[9] Barnhart and Etymonline date cathode ray to 1880, though the phenomenon was known from 1859, and cathode-ray tube to 1905.^[4][3] Modern dictionaries define it as the electrode where electrons enter a device from the outer circuit: it is the negative terminal of an electrolytic cell but the positive terminal of a primary cell or of a storage battery delivering current.^[8][10] In an electron tube it is the electrode that emits electrons.^[8][10]

Timeline

• 1834 – the path or surface by which current passes to the negative pole.^[2][3]
• 1840 – the negative pole.^[2]
• 1880 – cathode ray.^[3][4]
• 1905 – cathode-ray tube.^[3][4]

Meanings

Noun

1. The electrode at which electrons enter a device from the outer circuit.^[10][8]
2. The negative terminal of an electrolytic cell: Copper collected on the cathode during the experiment.^[10][8][9]
3. The positive terminal of a primary cell, or of a storage battery delivering current.^[10][8]
4. The electrode that gives off electrons in an electron tube or valve.^[10][8]

Word family

• cathodic
• cathodically
• cathodal
• cathodally
• cathodoluminescence
• anticathode
• photocathode
• cathode ray

Related words

• cation
• anode
• electrode
• exodus
• odometer

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e f g h i j k Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b c d e f g Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
5. ^ a b The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
6. ^ a b c Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
7. ^ a b c Ayto, John (2005), Word Origins: The Secret Histories of English Words from A to Z, 2nd ed., London: A & C Black
8. ^ a b c d e f g h Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
9. ^ a b Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
10. ^ a b c d e f Collins English Dictionary (2023), Glasgow: HarperCollins